The objective of the present study is focused on a comprehensive literature review of Sontecomapan Lagoon’s fish fauna, in order to have a better estimate of its species richness. According to previous studies, in the Sontecomapan Lagoon 115 species have been historically recorded, although two of them may correspond to misidentifications (Cathorops melanopus by Cathorops aguadulce, and Membras vagrans by Membras martinica). At least for 17 cases the taxonomic status has changed, the most relevant being Hypanus sabinus, Ctenogobius boleosoma, Gobionellus oceanicus, Mayaheros urophthalmus, Pseudoxiphophorus bimaculatus, and Microphis lineatus. The species level is uncertain for two cases, Tilapia sp. (in the present study considered as Oreochromis sp.) and Poeciliopsis sp. In both cases, the species to which these records can correspond is proposed. All species listed correspond to 26 orders, 41 families and 85 genera. Despite having only about 8.9 km2 of surface, the lagoon is one of the most species-rich estuarine ecosystems in the southern Gulf of Mexico, with approximately 13 % of the total fish species recorded for this area. Finally, according to the nonparametric methods for the estimation of species richness (Mao Tau, Chao 2, Jackknife 1, Jackknife 2, and Bootstrap), the total number of species expected for the lagoon could be between 119 and 127 species.